# Why does water disappear from an open container?

Sep 5, 2017

Magic....?

#### Explanation:

You have examined the physical process of evaporation.....i.e.

${H}_{2} O \left(l\right) r i g h t \le f t h a r p \infty n s {H}_{2} O \left(g\right)$

Now you had an open system, and the water vapour (or ethanol vapur, or whatever the solvent was) could expand to fill the room, and over 24-48 hours it entirely evaporated. Now you started with a solution, in which there was some involatile solute (what does $\text{involatile}$ mean?).

The solute came out of solution as the water (?) slowly evaporated, to give a solid residue.....

I bet the stuff was copper sulfate, which forms lovely blue crystals of $C u S {O}_{4} \cdot 5 {H}_{2} O$ on crystallization.....